So, when we're talking about sleeping on 600's, do people carry sleeping bags with them on these rides and could you fit one of these in the Barley?
Very few people carry sleeping bags. Teethgrinder sometimes does, I know. But he's a fruityloop who'll happily ride 1000k in a weekend on a mountain bike with panniers.
If it's a calendar ride, there will often be somewhere to sleep at the 350-400k mark. On the three coasts, this was also the arrivee, so you could drop your sleeping bag, do the first half of the ride, come back to the start, sleep and then do the second loop. Infinitely preferable!
I carried an ultralight cellular lofted bivvy bag on PBP, but that was more because of all the horror stories I'd heard about riders not being able to find somewhere under cover to nap. I had two sleeps inna tent/sleeping bag in Loudiac, provided by the lovely Liz. In the end, the bivvy bag stayed vacuum packed and unused, but it was nice knowing that if had really have had to, I could have put on all my clothes and climbed inside for a few hours sleep. It weighed 350g and was the size of a VHS cassette, fitted in one of my front panniers (carried on the rear for PBP).
On a calendar 600k with sleeping "facilities", all you really need is what you'd usually take on an audax and at least a change of shorts. On the BCM, Liz and I had the luxury of a change of shorts every 200k - that was fabulous.